includes/libs/CSSMin.php

   1 <?php
   2 /**
   3  * Minification of CSS stylesheets.
   4  *
   5  * Copyright 2010 Wikimedia Foundation
   6  *
   7  * Licensed under the Apache License, Version 2.0 (the "License"); you may
   8  * not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  *              http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software distributed
  14  * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  15  * OF ANY KIND, either express or implied. See the License for the
  16  * specific language governing permissions and limitations under the License.
  17  *
  18  * @file
  19  * @version 0.1.1 -- 2010-09-11
  20  * @author Trevor Parscal <tparscal@wikimedia.org>
  21  * @copyright Copyright 2010 Wikimedia Foundation
  22  * @license http://www.apache.org/licenses/LICENSE-2.0
  23  */
  24
  25 /**
  26  * Transforms CSS data
  27  *
  28  * This class provides minification, URL remapping, URL extracting, and data-URL embedding.
  29  */
  30 class CSSMin {
  31
  32         /* Constants */
  33
  34         /**
  35          * Maximum file size to still qualify for in-line embedding as a data-URI
  36          *
  37          * 24,576 is used because Internet Explorer has a 32,768 byte limit for data URIs,
  38          * which when base64 encoded will result in a 1/3 increase in size.
  39          */
  40         const EMBED_SIZE_LIMIT = 24576;
  41         const URL_REGEX = 'url\(\s*[\'"]?(?P<file>[^\?\)\'"]*)(?P<query>\??[^\)\'"]*)[\'"]?\s*\)';
  42
  43         /* Protected Static Members */
  44
  45         /** @var array List of common image files extensions and mime-types */
  46         protected static $mimeTypes = array(
  47                 'gif' => 'image/gif',
  48                 'jpe' => 'image/jpeg',
  49                 'jpeg' => 'image/jpeg',
  50                 'jpg' => 'image/jpeg',
  51                 'png' => 'image/png',
  52                 'tif' => 'image/tiff',
  53                 'tiff' => 'image/tiff',
  54                 'xbm' => 'image/x-xbitmap',
  55         );
  56
  57         /* Static Methods */
  58
  59         /**
  60          * Gets a list of local file paths which are referenced in a CSS style sheet
  61          *
  62          * @param string $source CSS data to remap
  63          * @param string $path File path where the source was read from (optional)
  64          * @return array List of local file references
  65          */
  66         public static function getLocalFileReferences( $source, $path = null ) {
  67                 $files = array();
  68                 $rFlags = PREG_OFFSET_CAPTURE | PREG_SET_ORDER;
  69                 if ( preg_match_all( '/' . self::URL_REGEX . '/', $source, $matches, $rFlags ) ) {
  70                         foreach ( $matches as $match ) {
  71                                 $file = ( isset( $path )
  72                                         ? rtrim( $path, '/' ) . '/'
  73                                         : '' ) . "{$match['file'][0]}";
  74
  75                                 // Only proceed if we can access the file
  76                                 if ( !is_null( $path ) && file_exists( $file ) ) {
  77                                         $files[] = $file;
  78                                 }
  79                         }
  80                 }
  81                 return $files;
  82         }
  83
  84         /**
  85          * Encode an image file as a base64 data URI.
  86          * If the image file has a suitable MIME type and size, encode it as a
  87          * base64 data URI. Return false if the image type is unfamiliar or exceeds
  88          * the size limit.
  89          *
  90          * @param string $file Image file to encode.
  91          * @param string|null $type File's MIME type or null. If null, CSSMin will
  92          *     try to autodetect the type.
  93          * @param int|bool $sizeLimit If the size of the target file is greater than
  94          *     this value, decline to encode the image file and return false
  95          *     instead. If $sizeLimit is false, no limit is enforced.
  96          * @return string|bool: Image contents encoded as a data URI or false.
  97          */
  98         public static function encodeImageAsDataURI( $file, $type = null, $sizeLimit = self::EMBED_SIZE_LIMIT ) {
  99                 if ( $sizeLimit !== false && filesize( $file ) >= $sizeLimit ) {
 100                         return false;
 101                 }
 102                 if ( $type === null ) {
 103                         $type = self::getMimeType( $file );
 104                 }
 105                 if ( !$type ) {
 106                         return false;
 107                 }
 108                 $data = base64_encode( file_get_contents( $file ) );
 109                 return 'data:' . $type . ';base64,' . $data;
 110         }
 111
 112         /**
 113          * @param $file string
 114          * @return bool|string
 115          */
 116         public static function getMimeType( $file ) {
 117                 $realpath = realpath( $file );
 118                 // Try a couple of different ways to get the mime-type of a file, in order of
 119                 // preference
 120                 if (
 121                         $realpath
 122                         && function_exists( 'finfo_file' )
 123                         && function_exists( 'finfo_open' )
 124                         && defined( 'FILEINFO_MIME_TYPE' )
 125                 ) {
 126                         // As of PHP 5.3, this is how you get the mime-type of a file; it uses the Fileinfo
 127                         // PECL extension
 128                         return finfo_file( finfo_open( FILEINFO_MIME_TYPE ), $realpath );
 129                 } elseif ( function_exists( 'mime_content_type' ) ) {
 130                         // Before this was deprecated in PHP 5.3, this was how you got the mime-type of a file
 131                         return mime_content_type( $file );
 132                 } else {
 133                         // Worst-case scenario has happened, use the file extension to infer the mime-type
 134                         $ext = strtolower( pathinfo( $file, PATHINFO_EXTENSION ) );
 135                         if ( isset( self::$mimeTypes[$ext] ) ) {
 136                                 return self::$mimeTypes[$ext];
 137                         }
 138                 }
 139                 return false;
 140         }
 141
 142         /**
 143          * Remaps CSS URL paths and automatically embeds data URIs for URL rules
 144          * preceded by an /* @embed * / comment
 145          *
 146          * @param string $source CSS data to remap
 147          * @param string $local File path where the source was read from
 148          * @param string $remote URL path to the file
 149          * @param bool $embedData If false, never do any data URI embedding, even if / * @embed * / is found
 150          * @return string Remapped CSS data
 151          */
 152         public static function remap( $source, $local, $remote, $embedData = true ) {
 153                 $pattern = '/((?P<embed>\s*\/\*\s*\@embed\s*\*\/)(?P<pre>[^\;\}]*))?' .
 154                         self::URL_REGEX . '(?P<post>[^;]*)[\;]?/';
 155                 $offset = 0;
 156                 while ( preg_match( $pattern, $source, $match, PREG_OFFSET_CAPTURE, $offset ) ) {
 157                         // Skip fully-qualified URLs and data URIs
 158                         $urlScheme = parse_url( $match['file'][0], PHP_URL_SCHEME );
 159                         if ( $urlScheme ) {
 160                                 // Move the offset to the end of the match, leaving it alone
 161                                 $offset = $match[0][1] + strlen( $match[0][0] );
 162                                 continue;
 163                         }
 164                         // URLs with absolute paths like /w/index.php need to be expanded
 165                         // to absolute URLs but otherwise left alone
 166                         if ( $match['file'][0] !== '' && $match['file'][0][0] === '/' ) {
 167                                 // Replace the file path with an expanded (possibly protocol-relative) URL
 168                                 // ...but only if wfExpandUrl() is even available.
 169                                 // This will not be the case if we're running outside of MW
 170                                 $lengthIncrease = 0;
 171                                 if ( function_exists( 'wfExpandUrl' ) ) {
 172                                         $expanded = wfExpandUrl( $match['file'][0], PROTO_RELATIVE );
 173                                         $origLength = strlen( $match['file'][0] );
 174                                         $lengthIncrease = strlen( $expanded ) - $origLength;
 175                                         $source = substr_replace( $source, $expanded,
 176                                                 $match['file'][1], $origLength
 177                                         );
 178                                 }
 179                                 // Move the offset to the end of the match, leaving it alone
 180                                 $offset = $match[0][1] + strlen( $match[0][0] ) + $lengthIncrease;
 181                                 continue;
 182                         }
 183
 184                         // Guard against double slashes, because "some/remote/../foo.png"
 185                         // resolves to "some/remote/foo.png" on (some?) clients (bug 27052).
 186                         if ( substr( $remote, -1 ) == '/' ) {
 187                                 $remote = substr( $remote, 0, -1 );
 188                         }
 189
 190                         // Shortcuts
 191                         $embed = $match['embed'][0];
 192                         $pre = $match['pre'][0];
 193                         $post = $match['post'][0];
 194                         $query = $match['query'][0];
 195                         $url = "{$remote}/{$match['file'][0]}";
 196                         $file = "{$local}/{$match['file'][0]}";
 197
 198                         $replacement = false;
 199
 200                         if ( $local !== false && file_exists( $file ) ) {
 201                                 // Add version parameter as a time-stamp in ISO 8601 format,
 202                                 // using Z for the timezone, meaning GMT
 203                                 $url .= '?' . gmdate( 'Y-m-d\TH:i:s\Z', round( filemtime( $file ), -2 ) );
 204                                 // Embedding requires a bit of extra processing, so let's skip that if we can
 205                                 if ( $embedData && $embed && $match['embed'][1] > 0 ) {
 206                                         $data = self::encodeImageAsDataURI( $file );
 207                                         if ( $data !== false ) {
 208                                                 // Build 2 CSS properties; one which uses a base64 encoded data URI in place
 209                                                 // of the @embed comment to try and retain line-number integrity, and the
 210                                                 // other with a remapped an versioned URL and an Internet Explorer hack
 211                                                 // making it ignored in all browsers that support data URIs
 212                                                 $replacement = "{$pre}url({$data}){$post};{$pre}url({$url}){$post}!ie;";
 213                                         }
 214                                 }
 215                                 if ( $replacement === false ) {
 216                                         // Assume that all paths are relative to $remote, and make them absolute
 217                                         $replacement = "{$embed}{$pre}url({$url}){$post};";
 218                                 }
 219                         } elseif ( $local === false ) {
 220                                 // Assume that all paths are relative to $remote, and make them absolute
 221                                 $replacement = "{$embed}{$pre}url({$url}{$query}){$post};";
 222                         }
 223                         if ( $replacement !== false ) {
 224                                 // Perform replacement on the source
 225                                 $source = substr_replace(
 226                                         $source, $replacement, $match[0][1], strlen( $match[0][0] )
 227                                 );
 228                                 // Move the offset to the end of the replacement in the source
 229                                 $offset = $match[0][1] + strlen( $replacement );
 230                                 continue;
 231                         }
 232                         // Move the offset to the end of the match, leaving it alone
 233                         $offset = $match[0][1] + strlen( $match[0][0] );
 234                 }
 235                 return $source;
 236         }
 237
 238         /**
 239          * Removes whitespace from CSS data
 240          *
 241          * @param string $css CSS data to minify
 242          * @return string Minified CSS data
 243          */
 244         public static function minify( $css ) {
 245                 return trim(
 246                         str_replace(
 247                                 array( '; ', ': ', ' {', '{ ', ', ', '} ', ';}' ),
 248                                 array( ';', ':', '{', '{', ',', '}', '}' ),
 249                                 preg_replace( array( '/\s+/', '/\/\*.*?\*\//s' ), array( ' ', '' ), $css )
 250                         )
 251                 );
 252         }
 253 }